One of radiographic examinations widely used for orthopedic and oral surgery examinations is a simple X-ray examination. X-rays passing through a human body are exposed to an X-ray film, generating a latent image in the X-ray film in proportion to intensity of a passing X-ray amount, in which silver bromide of photosensitive emulsion is converted into metallic silver by a developing process. According to an amount of this metallic silver, a change (shade density) of a blackening degree is obtained to form an X-ray image. The simple X-ray examination as stated above is used most frequently in orthopedic examinations.